The subject matter disclosed herein relates to device diagnostics, namely, in industrial process facilities, with particular discussion on techniques that improve efficiency of data collection for diagnostic testing of valve assemblies on a process line.
Industrial factories and like facilities operate process lines that may include many varieties of flow controls. Examples of these flow controls include pneumatic and electronic valve assemblies (also “control valves”) that regulate a flow of process fluid (e.g., gas and liquid). In conventional configurations, these valve assemblies have a number of components that work together to regulate flow of process fluid through the valve assembly. These components include a stem, a plug, a seat, and an actuator that couples with the stem to change the position of the plug relative to the seat. The components can also include various linkages and springs that ensure proper movement, e.g., of the stem and/or the plug. In some constructions, the valve assembly incorporate a valve positioner with electrical and/or electro-pneumatic components. During operation, the valve positioner instructs the actuator to change the position of the plug relative to the seat. Often, the valve positioner issues the instructions in response to control signals from a controller, e.g., that is part of a process control system (also “distributed control system” or “DCS”). The process control system manages operation of, inter alia, the valve assemblies to achieve the process parameters for the process line.
Problems with the valve assemblies may disrupt the process and/or prevent the process line from achieving the necessary process parameters. The resulting disruptions can lower yields and reduce quality. In large refineries, chemical plants, and power plants, disruptions can also lead to significant expense from process downtime that is necessary to troubleshoot and repair the problematic devices. Thus, plant operators have an interest to detect problems before the problems manifest in ways that can hinder sustainable operation of the process line. On the other hand, plant operators are adverse to allow diagnostic techniques that would take valve assemblies offline or permit interactions with the valve assembly that induce and/or adjust the settings of the valve assembly outside of those settings prescribed for the process.
Facilities and operators may allow techniques that collect data, but that do not interrupt operation of the valve assemblies. This data may include, for example, data that relates to operative variables including setpoint, pressure, position, and like information. This data is readily available, e.g., via the DCS, the valve positioner, and/or other components in the facility. While this data is helpful, however, processes are meant to minimize variations in operating variables to maintain stability and predictability of the process output. The stability of the process requires techniques to continuously collect data from the valve assemblies to increase the likelihood that the data collected will reveal observable movement in the components of valve assembly. This movement is critical for proper diagnosis of the device using many online diagnostics and related predictive maintenance techniques. Unfortunately, the vast number of valve assemblies in use in the facility, as well as limits on bandwidth on the systems/networks to gather data, can frustrate the process of data collection. These limitations can prevent diagnostic techniques to capture enough data to identify movement or other activities of the valve assemblies, let alone to observe problems with one or more valves assemblies on the process line.